package com.lzx.gateway.routers;

import cn.hutool.json.JSONUtil;
import com.alibaba.cloud.nacos.NacosConfigManager;
import com.alibaba.nacos.api.config.listener.Listener;
import com.alibaba.nacos.api.exception.NacosException;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.route.RouteDefinition;
import org.springframework.cloud.gateway.route.RouteDefinitionWriter;
import org.springframework.stereotype.Component;
import reactor.core.publisher.Mono;

import javax.annotation.PostConstruct;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.Executor;

@Component
@Slf4j
@RequiredArgsConstructor
public class DynamicRouteLoader {

    private final NacosConfigManager nacosConfigManager;
    private final RouteDefinitionWriter routeDefinitionWriter;

    private final String dataId = "gateway-routes.json";
    private final String group = "DEFAULT_GROUP";
    private final Set<String> routeIds = new HashSet<>();

    @PostConstruct //在Bean初始化之后执行
    public void initRouteConfigListener() throws NacosException {
        //1.项目启动，先拉取一次配置，并且添加配置监听器
        String configInfo = nacosConfigManager.getConfigService()
                                              .getConfigAndSignListener(dataId, group, 5000, new Listener() {
                                                  @Override
                                                  public Executor getExecutor() {
                                                      return null;
                                                  }

                                                  @Override
                                                  public void receiveConfigInfo(String configInfo) {
                                                      // 2.监听到配置变更，更新路由表
                                                      updateConfigInfo(configInfo);
                                                  }
                                              });
        //3.第一次读取到配置，也需要更新路由表
        updateConfigInfo(configInfo);

    }

    public void updateConfigInfo(String configInfo){
        log.debug("监听到路由信息={}",configInfo);

        //1.解析配置文件，转为RouteDefinition
        List<RouteDefinition> routeDefinitionList = JSONUtil.toList(configInfo, RouteDefinition.class);
        log.debug("解析后的路由信息为={}",routeDefinitionList);

        //2.删除旧的路由表
        for (String routeId : routeIds) {
            routeDefinitionWriter.delete(Mono.just(routeId)).subscribe();
        }
        routeIds.clear();

        //3.更新路由表
        for (RouteDefinition routeDefinition : routeDefinitionList) {
            //3.1更新路由表
            routeDefinitionWriter.save(Mono.just(routeDefinition)).subscribe();
            //3.2记录路由id，便于下一次更新时删除
            routeIds.add(routeDefinition.getId());
        }

    }
}
